Fix __ge__ and __gt__ comparison methods #22
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Quoting the Python documentation for sets: "The subset and equality comparisons do not generalize to a total ordering function. For example, any two nonempty disjoint sets are not equal and are not subsets of each other, so all of the following return False: a<b, a==b, or a>b." It is therefore not possible to define __ge__ as the inverse of __lt__ (and similarly __gt__ as the inverse of __le__), since this will give false positive results. Fix by implementing __ge__ and __gt__ using equivalent logic to that used in __le__ and __lt__. Signed-off-by: Michael Brown <mbrown@fensystems.co.uk>
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Do you have any queries or requested changes? Would it help if I opened an issue to report the original bug that is fixed by this patch? Thanks, Michael |
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@simonpercivall Any thoughts on this PR? |
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Until this issue is resolved here, may want to check out #38 |
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Quoting the Python documentation for sets:
"The subset and equality comparisons do not generalize to a total
ordering function. For example, any two nonempty disjoint sets are
not equal and are not subsets of each other, so all of the
following return False: a<b, a==b, or a>b."
It is therefore not possible to define ge as the inverse of lt
(and similarly gt as the inverse of le), since this will give
false positive results.
Fix by implementing ge and gt using equivalent logic to that
used in le and lt.
Signed-off-by: Michael Brown mbrown@fensystems.co.uk